Continuous casting mold

ABSTRACT

An open ended continuous-casting mold, from which the strand cast therein is conducted away from it along a curved path, has a generally straight mold cavity. The lower portion of the side of the cavity toward the center of curvature of the path is slanted outward, the upper and lower ends of the slanted portion being on a curve having approximately the same degree of curvature as the path, and a spring-loaded roll at the exit end of the mold is adapted to press the strand laterally toward the slanted portion.

United States Patent [72] Inventor Irving R051 2,692,410 10/1954 Chadwick et a1. 164/89 Morristown, NJ. 3,329,199 7/1967 Easton 164/83X [21] Appl. No. 700,509 3,339,623 9/1967 Rys et al. 164/83 [22] Filed 1968 Primary Examiner-J. Spencer Overholser [45 1 pagnted t d Assistant Examiner-R. Spencer Annear [73] Assgnee Concast corpora e Attorney-Sandoe, Neill, Schottler & Wikstrom New York, N.Y.

[54] CONTINUOUS CASTING MOLD 6 Claims, 3 Drawing Figs.

[52] 11.8. CI. 164/273, v ABSTRACT: An opemended continuous casting mold from 164/282 which the strand cast therein is conducted away from it along [51] Int. Cl B2211 11/12 a curved path has a generally straight mold cavity. The lower [50] Field of Search 164/82, 83, portion f the side f the cavity toward the center f curvature 283 of the path is slanted outward, the upper and lower ends of the slanted portion being on a curve having approximately the [56] References cued same degree of curvature as the path, and a spring-loaded roll UNITED STATES PATENTS at the exit end of the mold is adapted to press the strand 2,410,837 1 l 1946 Peters 164/83 laterally toward the slanted portion.

1 CONTINUOUS CASTING MOLD The present invention relates to the continuous casting of metal, such as steel, and particularly to an improved mold for such casting.

In continuous casting, molten metal is poured in the upper end of an open ended mold cavity. The mold is continuously cooled so that the periphery of metal in the mold solidifies to form a strand which emerges from the lower or exit end of the mold cavity, and as the strand leaves the mold more molten metal is poured into the top of the mold for casting a continuous strand. In known methods the casting is carried out in a substantially vertical line and to reduce the height and complexity of apparatus for subsequently handling and working the strand-rolling, shaping, finishing and/or cutting,for example the strand emerging from the moldis customarily conducted along a curved path and then straightened along a horizontal path where it can be worked more easily and economically.

It is also customary to oscillate the mold longitudinally a short distance-from about one-half to about two inches, for exampleto facilitate mold release and increase the casting rate.

In casting methods in which the strand is conducted from the mold along the curved path, curved molds are sometimes used so that the strand emerges in a curve conforming to the curved path. This avoids having to bend the fragile, newly formed strand, since bending it increases the possibility of the still-molten core breaking out of the strand and tends to cause surface defects. For casting with a curved mold, the mold is oscillated in an are having approximately the curvature of the path for the strand.

Molds with curved cavities, however, have not been completely satisfactory. Mold cavities are customarily provided with liners of copper because of its good heat-conducting properties: The curved copper mold liners have higher fabricating and maintenance costs than straight copper liners for straight mold cavities. In addition, proper aligning of a mold with a curved cavity is more difficult than properly aligning a mold with a straight cavity. However, the strand which emerges in straight condition from a straight mold cavity must then be bent into the curved path and this bending operation requires additional vertical space as compared with the vertical space requirement for machines having curved mold cavities. Thus, in known casting machines the benefits of conducting the strand along a curved path from the mold warrant the continued use of curved paths, but these benefits have been diminished by the above-described problems with the molds.

These problems are overcome with molds embodying the present invention. Specifically, molds of this invention are as economical to construct as conventional molds; are effective to shape the emerging strand into a curve; compatible with the curved path from the mold; and provide support for the strand in the lower portion of the mold which eliminates the problem of cross-sectional distortion. I

In accordance with the present invention the cavity of the mold is substantially straight and therlower portion of the side of the cavity, which is toward the center of curvature of the path for the strand, is slanted outward from a point approximately halfway between the intended level of metal in the mold cavity and the exit end of the cavity. The upper and lower ends of this slanted portion are on a curve having approximately the same degree of curvature as the path for the strand. Between these points, the slanted portion may either be straight or curved. Adjustable pressure means, suitably a spring-loaded pressure roll, is provided at the exit end of the cavity for pressing the strand laterally against the slanted portion. In this way the slanted portion guides the strand and provides support which suppresses wobbling and prevents crosssectional distortion. The pressure of the spring is adjustable to provide sufficient pressure for guiding the strand without squeezing it out of shape.

In addition, molds in accordance with this invention may be oscillated in a conventional manner, either in a straight line tangent to the curved path of the strand or in an arc approximately corresponding to the curve of path for the strand, and will shape the strand into a curve which is compatible with the curvature of the subsequent path to be followed by the strand so that the strand passes smoothly from the mold into the path without having to be bent and without being deformed or marred by the mold.

Further objects, advantages and features of the invention will be apparent in the following detailed description of illustrative embodiments depicted in the accompanying drawings wherein:

FIG. 1 is a schematic side elevation of a vertical section through a mold embodying the invention, showing a strand of metal cast by the mold and the upper end of the path for the strand away from the mold;

FIG. 2 is a horizontal section through a pressure roll and the bracket in which the pressure roll is mounted on a mold in accordance with the invention, but showing a particular configuration of the pressure roll for engaging the edge of a rectangular strand formed by a mold which is arranged so that the rectangular strand emerges edgewise relative to the curvature of the path from the mold; and

FIG. 3 is a view of a horizontal cross section through a pressure roll having a cross-sectional configuration for engaging the side of a rectangular strand formed by a mold which is arranged for the strand to emerge squarely with a side at right angles to the curvature of the path.

Referring the drawings, a continuous-casting mold 10, which is suitably cooled by conventional means, such as by circulating water through the mold body, has an open ended mold cavity 11. Molten metal from a tundish outlet 12, or other suitable source, is poured into the upper end 11a of the mold cavity, and the mold cools and solidifies the periphery of the metal to form a strand 13 which emerges from the lower, exit end 11b of the cavity. The emerging strand is then conducted away from the mold along a curved path shown as being defined by paired guide rolls l4 spaced to be at opposite sides of the strand at intervals along the desired path in a conventional manner. The center of curvature of the path for the strand is indicated at C; the radial line R1 indicates the radius.

When the strand emerges from the mold it is further cooled, to prevent the still molten core from remelting the solidified skin and to complete solidification, by suitable means such as water sprays 15 spaced along the path of the strand.

The level of molten metal in the mold is shown at 16. When the periphery of the metal solidifies to form the strand, which occurs about 3 or 4 inches below the level of the metal, the circumference of the strand shrinks, leaving a space 17 between the surface of the strand and the wall of the mold. Below the point at which the strand forms in the mold, the strand is therefore relatively loose in the mold and tends to wobble around in the mold as it passes through the lower portion of the mold. Since the skin of the strand is relatively thin at this point, and due to the lack of support along this portion of the strand and the wobbling, the configuration of strand produced by the cross-sectional configuration of the mold tends to become distorted; round strands become oval and square or rectangular strands become rhomboid. Elimination of this distortion is one of the features and advantages of molds of the present invention.

In accordance with the invention, the mold cavity 11 extends straight through the mold 10, but the lower portion of the wall of the cavity, at the side toward the center C of the curved path for the strand, is slanted outward from a point 18 about halfway between the intended level 16 of metal in the mold and the exit end 11b. The slanted portion of the cavity wall is identified by the number 20. Its upper end, 18, is below, and preferably close to, the point at which the strand is sufficiently formed for its circumference to have shrunk in from the wall of the mold and will be at a point on the cavity wall in the midportion between the intended level 16 of metal and the exit end 11b.

The mold cavity 11 is preferably made quite short in order to reduce as much as practicable the length of the cavity below the level at which the circumference of the strand has receded from the cavity wall to leave a space 17, because this space has an insulating etfect which retards the cooling that is necessary to prevent the still molten core from remelting the solidified skin. In one example, with a mold cavity about 15 inches long, the level 16 of metal will be about 3 inches down from the upper end 110, the strand will begin to shrink away from the cavity wall about 3 or 4 inches below that, and the upper end 18 of the slanted portion 20, which is preferably at or slightly below-the start of shrinkage, is about 6 or 7 inches below the level 16. In other words, in a preferred form of the mold in which the mold cavity is about 15 inches long, the slanted portion 20 is about or 6 inches long so that its upper end is about halfway between the intended level 16 of metal in the mold and the exit end llb.

As shown in FIG. 1, the upper end 18 of the slanted portion 20 and its lower end at exit end 11b of the cavity are on a curve, radius R2, having the same center C as the curved path for the strand. The radius R1 of the path is relatively large, on the order of from 20 to 40 feet, for example, compared with the length of slanted surface 20, which may be from about 6 inches for a mold cavity inches long to about 13 inches for one 30 inches long. Consequently, the curvature of the segment of a curve, radius R2 through the upper and lower ends of the slanted surface is very slight so that the length of the slanted surface may suitably be made fiat.

At the bottom of the mold, at the edge of the exit end 11b away from the center C, a pressure roll 21 is arranged to bear against the strand l3 and urge it laterally toward the slanted surface 20 so that the strand rides down along the slanted portion 20. As noted above, the gap 17 resulting from the shrinkage of the strand leaves it unsupported in the usual form of mold, whether curved or straight, so that its configuration becomes distorted. With the mold of the present invention, however, the strand being pressed against one side of the mold cavity by the pressure roll 21, is pressed against one side of the mold which thus prevents wobbling and provides firm support for the contour at one side of the strand so that the strand retains its cast configuration.

Referring to FIGS. 1 and 2, the pressure roll, 21 in FIG. 1, and 21a in FIG. 2, is mounted in a bracket 22, which is slidably supported in a frame 23 attached to the lower end of the mold, and springs 24 bearing on the bracket 22 urge the bracket and pressure roll, 21 or 21a in a direction laterally across the lower end of the mold. As indicated in FIG. 2, the ends of an axle 25, of the pressure roll, 21 or 21a, are joumaled through the opposite sides of the bracket 22 and extend outward from the bracket into elongated slots 26 respectively in opposite walls of the frame 23. The slots 26 extend parallel to the bottom of the mold to permit the bracket and roll to slide toward or back from a strand, 13 in FIG. 1 and 13a in FIG. 2, emerging from the mold. The springs 24 are mounted between the rear of the bracket 22 and a plate 27 which is slidably mounted by pins 27a projecting respectively from its opposite edges into the slots 26, and a setscrew 28 threaded through a cross member 29 of the frame 23 bears against the plate 27 for adjusting the position of the plate, and hence the pressure with which the springs 24 urge the pressure roll against the strand.

The cross-sectional configuration of the mold cavity 11, including the slanted portion 20, is selected to produce a casting having the desired cross-sectional configuration, round, square, rectangular or any other desired configuration, and the pressure roll 21 is provided with a compatible contour. FIG. 2 shows a roll 21a contoured for properly engaging a rectangular strand 13a which has been formed by a mold aligned to cast the strand so that it emerges from the mold edgewise to the center C of the curved path from the mold with opposite comers of its rectangular shape respectively at the inside and outside of the curve. In this instance, the roll 21a has a central V-shaped groove to'match the configuration and angular alignment of the strand 13a.

FIG. 3 illustrates an alternative roll 21b that has a suitable contour for engaging a rectangular strand 13b formed by a 'mold arranged to issue the strand with opposite flat sides respectively at the inside and outside of the curved path from the mold.

Molds constructed in accordance with this invention are particularly adapted to be oscillated in the conventional manner, either straight up and down or in an are around the center C. Customarily, continuous-casting molds are oscillated a distance of from about half an inch to about 2 inches, and they are usually driven to be moved downward at approximately the same rate the strand is carried 'away from the mold and to be moved upward at a faster rate. Molds of this invention are suitably operated in this manner and are mounted so that at the bottom of their oscillatory stroke the portion of the strand emerging from between the pressure roll 21 and the opposite bottom edge of the cavity are aligned with the upper end of the path. On the upward stroke of the mold, whether in a straight line or in an arc, the movement of the mold, the pressure roll 21 and the slanted portion 20 cooperate to shape the portion of the strand being formed in the mold into an approximation of the desired curve. On the down stroke, movement of the mold, pressure roll and slanted portion support the strand and guide it into the curved path. As shown, the edge of the exit end 11b, at the inside, relative to the cured path, may be beveled as indicated at 30 to avoid chance of its gouging or marking the strand on the downward stroke of the mold; alternatively or supplementally, a free-rolling guide roll may be mounted at that edge for the same purpose.

It is to be understood that the embodiment of the invention shown in the drawings and described in detail above is illustrative only and that modifications and variations may be made in the structure and mode of operation thereof without departing from the scope of the invention defined by the following claims.

I claim:

1. An improved mold for use in continuous casting wherein molten metal-poured in one end of an open ended cavity of a mold is peripherally cooled to form a strand, the surface of which shrinks away from the cavity wall as the strand forms, and wherein the strand emerges from the exit end of the mold cavity and is conducted away from the mold through a guide means for forming a curved path, said improved mold comprising a substantially straight mold cavity with the lower portion of the side of the cavity toward the center of curvature of said path being slanted outward, the upper end of said slanted portion being located less than halfway between the exit end and said one end of the mold so as to be below the level at which the surface of the strand begins to shrink away from the cavity wall and being at a point in the mold approximately halfway between the intended level of metal in the mold cavity and the exit end, said slanted portion extending to the exit end of the mold cavity, the upper and lower ends of the slanted portion being on a curve having approximately the same degree of curvature as said path for the strand, and means for urging the strand laterally toward and into contact with the slanted portion.

2. The improved mold of claim 1 in which the length of said slanted portion is straight between its ends.

3. The improved mold of claim 1 in which the length of said slanted portion is curved to approximately the same degree as the path for the strand.

4. The improved mold of claim 1 in which the upper end of said slanted portion is between about 6 to 7 inches below the intended level of metal in the mold.

5. The improvedmold of claim 1 in which said means for urging the strand laterally comprises a roll at the side of the exit end of the mold cavity away from the center of said path, and spring means for urging the periphery of the roll against a strand emerging from said exit end.

6. The improved mold of claim 5 which includes means for adjusting the pressure of said spring means on the roll. 

1. An improved mold for use in continuous casting wherein molten metal poured in one end of an open ended cavity of a mold is peripherally cooled to form a strand, the surface of which shrinks away from the cavity wall as the strand forms, and wherein the strand emerges from the exit end of the mold cavity and is conducted away from the mold through a guide means for forming a curved path, said improved mold comprising a substantially straight mold cavity with the lower portion of the side of the cavity toward the center of curvature of said path being slanted outward, the upper end of said slanted portion being located less than halfway between the exit end and said one end of the mold so as to be below the level at which the surface of the strand begins to shrink away from the cavity wall and being at a point in the mold approximately halfway between the intended level of metal in the mold cavity and the exit end, said slanted portion extending to the exit end of the mold cavity, the upper and lower ends of the slanted portion being on a curve having approximately the same degree of curvature as said path for the strand, and means for urging the strand laterally toward and into contact with the slanted portion.
 2. The improved mold of claim 1 in which the length of said slanted portion is straight between its ends.
 3. The improved mold of claim 1 in which the length of said slanted portion is curved to approximately the same degree as the path for the strand.
 4. The improved mold of claim 1 in which the upper end of said slanted portion is between about 6 to 7 inches below the intended level of metal in the mold.
 5. The improved mold of claim 1 in which said means for urging the strand laterally comprises a roll at the side of the exit end of the mold cavity away from the center of said path, and spring means for urging the periphery of the roll against a strand emerging from said exit end.
 6. The improved mold of claim 5 which includes means for adjusting the pressure of said spring means on the roll. 